There is a need for better methods to grow and market small trees. There are two primary methods to grow small trees for transplanting: in containers and in the ground. In the container method 4 to 6 year old trees are grown and sold in shallow containers that are open on the top and have a bottom, and are 8 to 20 inches in depth with a diameter of 8 to 20 inches. These trees are typically 6 feet to 12 feet tall at time of sale. The root structure present in the container is frequently compromised. The root mass may be too small to fully anchor the tree in the soil when permanently planted, requiring that the planted tree be supported by stakes and constraints to prevent leaning of the tree, and to encourage proper root development. Trees grown in these containers frequently develop dense tangled root structures. When planted such trees become ‘root-bound’, wherein the roots do not develop normally to provide adequate anchoring or nourishment for the tree above ground. When planted, root-bound trees will frequently develop girdling roots. A girdling root circles the base of the tree and can choke nutrient flow from the roots up to the limbs of the tree, and result in the eventual death of the tree.
Commercial nurseries also grow trees in the ground for 3 to 10 years, or longer. These trees are then dug up as a root ball, either with a hydraulic tree spade or by hand, and the root ball structure and roots trimmed with pruning tools. A significant portion of the root structure can be lost in this process. The root ball is either wrapped in burlap or the like or placed in a container with a closed bottom. The root ball is typically small compared to the size of the tree growing from the root structure, particularly if the digging is done manually. Growing and selling trees in this manner has several drawbacks such as the need for significant acreage, the risk of transplant shock (i.e., death of the tree after permanent planting), the amount of labor needed to dig the tree from the nursery and to replant the tree, the need for expensive equipment to move larger trees, the damage done to the root structure when digging the tree from the nursery, the need for supports and anchors for larger trees once planted, and an inadequate root system to provide nutrients to the tree after planting. Typically, trees grown and planted in this manner may take 2 to 3 years before the root structure is re-developed enough to encourage rapid growth of the tree above the ground.
Another method to grow trees in the ground for marketing is the bare-root method. In this method, trees are grown from seed or germinated seed in well tilled aerated soil. The trees are grown in close proximity to one another. The trees are grown for 1 to 3 years and then dug up with mechanized equipment in the spring or late fall. The soil is removed from the root structure and the root structure is keep moist. Typically, the bare root trees are bundled together in quantities up to 100. The bare tree roots are wrapped with moist packing and are immediately delivered to a customer. Drawbacks of this method include the possibility of the roots drying out before planting causing death, damage to the microscopic root structure which can cause transplant shock, and need for greater expertise when planting. Some of these drawbacks can be overcome in large scale operations through the use of specialized techniques and/or equipment. However, in small scale operations (200 trees or less), these problem persist.
Therefore, there exists a need for robust, cost effective and environmentally friendly methods to raise and market small trees that are 2 to about 6 feet tall.